Milk. 
291 
5. ^[Uh Globules. — The milk globules are small round or egg- 
shaped bodies, which enclose in a thin shell of casein a mixture 
of several fattv matters. They are somewhat lighter than milk, 
and consequently rise on the surface when milk is set aside in 
skimming-dishes. 
In the degree in which the milk globules are thrown up and 
removed in the shape of cream, milk gets less opaque, and as- 
sumes a more decidedly blue colour. 
Bv churning cream the casein shells are broken, and the con- 
tents of the milk-globules made into butter. 
Butter consists mainly of a mixture of several fats, amongst 
which palmitin, a solid crystallizable substance, is the most im- 
portant. . 
Palmitin, with a little stearine, constitutes about 68 per cent, 
of pure butter. Mixed with these solid fats are about 30 per 
cent, of olein, a liquid fatty matter, and about 2 per cent, of 
odoriferous oils. The peculiar flavour and odour of butter are 
owing to the presence of this small proportion of these peculiar 
oils, viz., butyrin, caproin, and caprylin. 
In butter, as it comes on our table, w e find besides these fatty 
matters about IG to 18 per cent, of water; 1 to 2 per cent, of 
salt ; and variable small quantities of fragments of casein shells. 
The more perfectly the latter are removed by kneading under 
water, the better butter keeps ; for casein on exposure to air in a 
moist state, especially in warm weather, becomes rapidlv changed 
into a ferment, which, acting on the last-named volatile fatty 
matters of butter, resolves them into glycerine and butyric acid, 
CgHg04 ; caproic acid, C12H12O4; and caprylic acid, 0,^ H,s O4. 
The occurrence of these volatile, uncombined fatty acids in 
rancid butter not only spoils the flavour, but renders it more or 
less unwholesome. 
On Dairy Airangements. 
Having described the principal properties, and given the com- 
position of all the chief constituents of milk, we offer a few 
observations on dairy arrangements, more especially on the means 
for keeping milk and cream in the best condition. It is hardly 
necessary to remind the reader that too much attention cannot be 
bestowed upon keeping the dairy itself, as well as the milk-pails, 
pans, and other dairy utensils, scrupulously clean. But as some 
people have an impression that cleanliness can only be main- 
tained in the dairy when almost unlimited quantities of water are 
used for washing the floor and cleaning the various utensils, a 
few words of caution against the injudicious and wasteful em- 
ployment of water, may not be out of place. Of course there 
